1. Field of the Invention
The present invention relates to twin-bedded warp knitting machines, and in particular, to a twin bedded machine which permits the needle beds to be spaced closer together in the knock-over position than the width of the flattened end portion of a guide which performs an underlapping operation.
2. Description of the Relevant Art
Conventional twin-bedded warp knitting machines include a plurality of commonly swingable guidebars wherein at least one guidebar forms stitches across both needle beds and generally, at least two guidebars, singly or together, perform an underlap displacement. The guides generally have a flat end portion which runs parallel to the swinging plane of the guide and the needle beds, being parallel to each other, are provided with a separation which is slightly larger than the width of the end portions of the guides.
A typical warp knitting machine of this type is disclosed in German Patent No. 1,208,030. The latch needles disclosed therein on both needle beds are disposed in a position essentially parallel to each other. The guidebars are driven by means of a three stroke eccentric cam so that for each cycle of the needles three cycles of the guidebar swinging movement are provided. In machines of this type, it does not matter if the distance between both the needle beds is large or small, since the underlapping displacement of the guides always occurs when the needles of a needle bed are in the knock-over (lowest) position.
In another known twin-bedded warp knitting machine such as that disclosed in Germany Offenlegungsschrift No. 2,134,279 the guidebar driving mechanism is so arranged that a single forward and backward swinging movement of the guidebars corresponds to a single working cycle of the needle beds. These single stroke machines have a decided advantage over the three-stroke machines since it is possible to operate them at much higher working speeds. However, they are unable to manufacture short pile ware, since the substantially parallel orientation of the needle beds must provide a substantial distance therebetween in order that the corresponding guides can move between them to perform the required underlapped displacement. It is therefore a requirement that the minimum separation between the needles must be equal to or slightly greater than the width of the bottom portion of the guides plus a little extra to allow for a certain amount of play in the movement of the guides and needle bed in order that the guides may be freely displaced during the displacement movements of the guides. When two or more simultaneous guides must be displaced at the same time, additional distance must be allowed between the needle beds in order to provide collision free displacement motion therebetween. By rotating the guides used for the underlap displacement by ninety degrees it is possible to reduce the distance required between the needle beds during the underlap displacement movement which is measured perpendicular to the needle bed. However, this requires that each needle bed leaves sufficient space for movement of this guide in the swing direction so that only every third needle space may be occupied with a needle. Therefore, the overall result is a comparatively course goods which will still have a relatively long pile.
Another twin-bedded warp knitting machine is disclosed in U.S. Pat. No. 3,221,520 issued to Bassist on Dec. 7, 1965. Provision is made therein to adjust the separation between the needle beds. Each of the three guides are separately driven and the centrally disposed guidebar alone performs an underlap displacement and swings between both needle bars. In this embodiment the needles are attached to the levers with a relatively large leverage so that the movement of the needles is substantially straight and parallel to each other.